Many individuals desire a “bright” smile and white teeth, and consider dull and stained teeth cosmetically unattractive. Unfortunately, without preventive or remedial measures, stained teeth are almost inevitable due to the absorbent nature of dental material. Everyday activities such as smoking or other oral use of tobacco products, and eating, chewing or drinking certain foods and beverages (in particular coffee, tea and red wine), cause undesirable staining of surfaces of teeth. Staining can also result from microbial activity, including that associated with dental plaque. The chromogens or color causing substances in these materials become part of the pellicle layer and can permeate the enamel layer. Even with regular brushing and flossing, years of chromogen accumulation can impart noticeable tooth discoloration.
A tooth is comprised of an inner dentin layer and an outer hard enamel layer that is the protective layer of the tooth. The enamel layer of a tooth is naturally opaque, and white or a slightly off-white color. The enamel layer is composed of hydroxyapatite mineral crystals that create a somewhat porous surface. These hydroxyapatite crystals form microscopic hexagonal rods or prisms that make up the enamel surface. As a result, the surface of the enamel presents microscopic spaces or pores between the prisms. Without limiting the mechanism, function, or utility of the present disclosure, it is believed that this porous nature of the enamel is where discoloring substances permeate the enamel and discolor the teeth.
To combat staining and brighten or restore the natural enamel color, products containing bleaching materials are commercially available for professional and consumer use. The most commonly accepted chemicals used in teeth whitening today are peroxides. Peroxides are generally deemed safe from a physiological standpoint, and can be effective to whiten teeth. Such peroxides include hydrogen peroxide, carbamide peroxide, sodium perborate, and sodium percarbonate. When these peroxides are in appropriate contact with teeth they will usually oxidize stains, rendering the teeth whiter.
Professional dental treatments frequently include a tooth surface preparation such as acid etching followed by the application of highly concentrated bleaching solutions (e.g. up to 37% hydrogen peroxide) and/or the application of heat or light. (See, e.g., U.S. Pat. Nos. 5,425,953 and 5,766,574.) These procedures provide rapid results, but are expensive, and often require several trips to the dentist. In many cases, the patient's lips are uncomfortably retracted during the entire treatment and the patient is confined to sitting in the dental chair.
Alternatively, at home bleaching systems can be used. These systems have gained significant popularity in the past decade because of reduced cost, and increased convenience.
Current home treatment methods include abrasive toothpastes, toothpastes that produce oxides, whitening gels for use with a dental tray and whitening strips. The effectiveness of such techniques depends on a variety of factors including the type and intensity of the stain, the type of bleaching agent, contact time of the bleaching agent on the teeth, the amount of available bleaching active in the composition the ability of the bleaching agent to penetrate the tooth enamel, and consumer compliance. Effectiveness is also dependent on the amount of bleaching active in the composition, the ability of the active to be released during use, and the stability of the active in the product. However, the effectiveness of many of these treatments is adversely affected because of deficiencies in one or more factors relating to the composition and consumer compliance.
Biofilms form when bacteria adhere to surfaces in some form of watery environment and begin to excrete a slimy, glue-like substance that can stick to all kinds of materials—metals, plastics, soil particles, medical implant materials, biological tissues. Biofilms can be formed by a single bacterial species, but biofilms more often consist of many species of bacteria, as well as fungi, algae, protozoa, debris, and corrosion products. Essentially, a biofilm may form on any surface exposed to bacteria and some amount of water. Dental plaque is a yellowish biofilm that builds up on the teeth. Biofilms contain communities of disease-causing bacteria and their uncontrolled accumulation has been associated with cavities and gum disease (both gingivitis and periodontitis).
There is thus a need for novel oral compositions and methods that may inhibit staining, acid erosion, and/or biofilm formation.